Clinical Perspective with Dr. Sushil Beriwal: We Must Push Beyond Current Radiation Treatment Limits | Varian

We talked with Dr. Sushil Beriwal, Vice President, Medical Affairs, Multidisciplinary Oncology, for Varian, about the opportunities in radiation therapy. He shared his insights on limitations of radiation oncology technology today, opportunities for technology advances, and why every gray matters to patient outcomes.

Q: What are the limitations of radiation oncology technology today?

A: Innovations in radiotherapy over the last quarter century have resulted in tremendous gains in our ability to target tumors very precisely and accurately, while sparing nearby healthy tissues to a significant degree. The development of techniques like intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) have led to better outcomes for patients, yet both have some limits.

A traditional IMRT approach can only utilize so many beam angles before the treatment becomes too long to be practical. A VMAT approach can sometimes overcome this limitation of IMRT, but you are limited in modulation from specific angles and can struggle to control low-dose radiation to healthy tissue. Each of them – IMRT and VMAT – involves tradeoffs between practicality and conformity, a term for how well a radiation dose distribution targets a tumor and spares surrounding healthy tissue.

Q. Cancer survival has improved, isn’t that success?

A. As more cancer patients survive and live longer, it becomes very important that we continue to improve the quality of their post-treatment lives and further reduce the risk of morbidities and even mortality from long term effects of treatments.

We know, for example, that during treatment for breast or lung cancer, each gray (Gy) – a measure of radiation dose – that reaches the heart increases the relative risk of cardiac morbidity by 5-7 percent, and cardiac mortality by 1-2 percent.^i,ii,iii Even small improvements in dosimetry can have an important impact.

There’s no doubt that innovations like IMRT and VMAT have led to better outcomes for patients, both in terms of tumor control and reductions in toxicity. These approaches have also reduced the risk of more severe, grade 3 side effects, which can lead to lasting complications of cancer treatment. We have achieved reductions in unwanted damage to the lungs, the salivary glands, and the bowel after treatment for lung, head & neck, and gynecological cancer, respectively.^iv,v,vi With breast cancer treatment, we have learned to limit the dose that reaches the heart, reducing the risk of later cardiac side effects.^vii

However, with more cancer patients surviving and living longer, there's a growing need to continue reducing chronic morbidities, as many patients still experience significant impacts on their quality of life.

We must not accept that what we have now is as good as it gets.

Q. What’s next for radiation oncology treatment?

A. Studies suggest that hybrid techniques such as the combination of VMAT and IMRT, when compared to IMRT or VMAT, could offer clinical advantages.^viii,ix,x Today, however, a process for harnessing the strengths of both approaches – the speed and efficiency of VMAT and the direction control of IMRT – requires complex planning, extensive preparation, and delivery of two separate treatment plans. It is simply too cumbersome and resource-intensive for clinical practice.

The next generation of radiotherapy treatment technology must solve this problem. It must enable clinical teams to efficiently plan, optimize, and deliver radiation therapy to take personalized radiation treatment to the next level.

We also need to consider how to extend the limits of our multi-leaf collimator – which shapes the radiation beam to match the contours of the tumor to enhance treatment delivery. Today, we sometimes compromise coverage of internal mammary nodes to avoid greater risk to the heart and lung – a trade-off that we hope to minimize to attain an optimal therapeutic ratio. Adding dynamic rotation, for example, could add another degree of freedom, potentially enabling better conformity for targets like the chest wall when treating breast cancer, and controlling modulation at specific gantry angles to better spare nearby healthy tissue and organs.

We must improve speed by developing advanced algorithms optimized for the graphics processing units (GPUs) that will drive new hardware capabilities to transcend the technology limitations we have today with VMAT and IMRT. Additionally, we must add more flexibility and control while incorporating integration and automation to streamline the planning process and treatment delivery so that treatments, simple or complex, become clinically feasible in any radiation oncology department. Such an integrated innovation could have the power to usher in a new era of even more personalized radiotherapy treatment. And in the end, that’s what we all want. We want to help bring about a world without fear of cancer.

I am proud to be working alongside members of a global consortium, consisting of radiation oncology thought leaders to solve these problems. We are looking at ways of creating new technology that unlocks new possibilities in dose modulation to help clinicians maximize plan quality and easily reduce dose to organs at risk, and plan complex cases in less time. We fervently hope that our efforts will benefit many of the 35 million people who will develop cancer annually by the year 2050.

Sushil Beriwal, MD, MBA, FASTRO, FABS, FICRO, is Vice President, Multidisciplinary Oncology, Medical Affairs for Varian and the academic chief at Allegheny Health Network and a professor of radiation oncology at Drexel University. He specializes in gynecologic, breast, and prostate cancers, with an emphasis on high-dose rate brachytherapy for cervical, uterine, vaginal, and breast cancers, along with prostate seed implantation, image-guided radiation therapy, and intensity-modulated radiation therapy. He has published more than 350 peer-reviewed manuscripts, served as senior editor for the International Journal of Radiation Oncology - Biology - Physics (Red Journal), and was on the editorial board for the journal Brachytherapy. He has the distinction of being recognized as a fellow by four national and international societies, including the American Society for Radiation Oncology (ASTRO), American Brachytherapy Society (ABS), the Indian College of Radiation Oncology (ICRO) and the American College of Radiation Oncology (ACRO).

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